Pipe forming machine



Sept. 14, 1965 F. E. MAR-HN 3,205,550

PIPE FORMING MACHINE Filed June 18, 1965 4 sheets-sheet 1 l Ik INVENTOR,22m/0 i. A44/erw Z/,uf 4free/vins' iwi Sept. 14,1965 F.E.MART|N PIPEFORMING MACHINE INVENTOR Fun/0 MAW-nv' Sept. 14, 1965 F. E. MARTIN PIPEFORMING MACHINE 4 Sheets-Sheet 3 Filed June 18, 1965 INVENTO F4 arp IMnir/M Sept. 14, 1965 F. E. MARTIN 3,205,550

PIPE FORMING MACHINE Filed June 18, 1963 4 Sheets-Sheet 4 INVENTOR.Fun/D i, Mier/N' f77-UPN! United States Patent O 3,295,550 PIPE FORMINGMACHINE Floyd E. Martin, 1800 Al Rey Drive, Concord, Caiif. Filed June1S, 1963, Ser. No. 288,694 11 Claims. (Ci. 2532) The invention isparticularly concerned with a machine for use in forming a pipe ofconcrete, either reinforced or not, within a ditch having side walls anda bottom.

There have been a number of machines and methods employed for pouringconcrete pipe in situ, particularly in a carefully exacavated ditch, andthere have been many systems and devices utilized for providing pipe ofthat sort formed elsewhere and then installed later in the ditch andconnected for use.

All of the previously utilized arrangements, so far as I know, have beenburdened with a number of disadvantages, one of which is the difficultyof providing a relatively straight pipe in the sense of a continuousinterior surface which has little or no impedance to hydraulic ow. Itwill be appreciated that even relatively slight changes in contour ofvarious different portions of the pipe and other interior roughnessimpede the hydraulic flow to such an extent that pipes are normallyspecied of somewhat larger diameter than is actually necessary in orderto make sure that the hydraulic flow losses are not too great.

It is therefore a principal object of my invention to provide a pipeforming machine capable of use in forming a pipe in a pre-excavatedditch in such a fashion that the resulting pipe is interiorly quitecontinuous and smooth so that it has a good hydraulic flowcharacteristic, so good as to permit the use of .a pipe smaller indiameter than usual.

Another object of the invention is to provide a pipe forming machinewhich can readily be utilized under varying soil and environmentalconditions.

A still further object of the invention is to provide a pipe formingmachine which can be made effective to provide pipe in a number ofdifferent sizes and contours.

A still further object of the invention is to provide a pipe formingmachine in which the customary contours can be poured without unduediiticulty.

A still further object of the invention is to provide a pipe formingmachine which can be utilized continuously to pour a relatively longpipe, certain portions of the machine being utilized repeatedly as themachine progresses.

A still further object of the invention is to provide a pipe formingmachine so arranged and constructed that the poured pipe is of excellentquality as to homogeneity and finish and is substantially devoid of airpockets and the like,

A still further object of the invention is to provide a pipe formingmachine which holds quite rigorously to the intended pipe shape andcontour.

A further object of the invention is in general to improve pipe formingmachines.

Other objects together with the foregoing are attained in theembodiments of the invention described in the accompanying descriptionand illustrated in the accompanying drawings, in which:

FIGURE l is a cross section on a vertical longitudinal plane through thepipe forming machine of the invention;

FIGURE 2 is a cross section on a transverse vertical plane showing themachine of FIGURE l, the plane of section being indicated by the line2--2 of FIGURE l;

FIGURE 3 is a transverse cross section on a vertical -plane through aportion of the machine, the plane of section being indicated by the line3-3 of FIGURE l;

FIGURE 4 is a View similar to FIGURE 3, the plane 3,205,550 PatentedSept. I4, 1965 of section being indicated by the line 4-4 of FIGURE l;

FIGURE 5 is a View similar to FIGURE 3, but showing some of the interiorparts in position for removal;

FIGURE 6 is a longitudinal section on a vertical plane of a modifiedform of pipe forming machine pursuant to the invention;

FIGURE 7 is a cross section, the plane of which is indicated by the line'7-7 of FIGURE 6;

FIGURE 8 is a fragmentary plan of a portion of the device, the viewbeing taken on the line 8 8 of FIG- URE 6;

FIGURE 9 is a fragmentary cross section, the plane of section beingindicated by the line 9 9 of FIGURE 8, and showing a dolly for use withthe machine; and

FIGURE lO is a fragmentary elevation of the structure shown in FIGURE 9.

In one typical environment the machine is utilized in a ditch 6 formedin the earth 7 and having a particular contour designed for the job inview. The ditch has or is excavated as nearly as possible to anappropriate semicircular bottom contour 8, this contour being that ofthe expected external diameter of the finished pipe. The excavatedbottom 8 in the earth is tangent at its horizontal diameter to theparallel, vertical side walls 9 and 11 likewise excavated as accuratelyas reasonable in the earth in which the pipe is to be formed. Inpractice, these contours are not usually of strict geometric character,but are made to approximate the indicated configuration as well as maybe under all circumstances. The depth of the bottom 8 from the groundsurface is arranged according to the survey for the pipeline.

In accordance with the invention, a tube 13 is initially disposed in theditch. This conveniently is fabricated of a somewhat flexible ordeformable material such as metal plate and is generally symmetricalabout a center line 14 which is also the center of the arcuate ditchbottom 8. The -center line 14 is often slightly inclined to thehorizontal, although it is illustrated as horizontal herein. The tube 13is fabricated in any of the usual ways, such as by -bending and welding,from commercial plate. It has a circular cylindrical configurationapproximating the intended internal diameter of the resulting pipe.

The tube 13 is not a complete circular section, but rather is providedwith a gap 15 extending longitudinally from one end of the tube 13 tothe other. The gap 15 iS closed by a separate arcuate plate 16 of thesame curvature as the balance of the tube. The plate is convenientlyreinforced by a stiifener 17 and is of an arcuate extent substantiallyto abut the sides of the gap 15 with but minor clearance between theparts.

To assist in supporting the plate 16 and also for other reasons, theinterior of the tube 13 is provided with a pair of longitudinallyextending angles 18 and 19 so disposed with respect to the gap ends ofthe tube I3 las to afford guideways or rails to support the overlappingedges of the arcuate plate 16.

In and of itself, the tube 13, although relatively rigid in alongitudinal or axial direction, is not particularly true to form incross sectional shape. For that reason, one or more sustaining frames 21are provided. Each of these is conveniently fabricated of metal tubingand for part of its configuration has an arcuate contour 22 supplementedby other arcuate contours 23 and 24. The portions 23 and 24 areinterrupted so as to afford adequate clearance with respect to thelongitudinally extending angles 18 and 19. In addition, the arcuateportions 22, 23 and 24 are interconnected by chordal intermediate tubes26 and 27 arranged substantially in parallelism. Each of the sustainingframes 21 is likewise provided with a cross member 2S so that theconfiguration of the sustaining frame is well fixed The envelope curveof the various arcuate portions 22,

3 23 and 24 is that desired for the interior of the tube 13, but thechordal portions 26 and 27 have a transverse dimension substantiallyless than the diameter of the curved portions. This is so that one ormore of the sustaining frames can be turned horizontally and introducedinto the tube longitudinally. This is readily accomplished because ofthe reduced transverse dimension of the chordal portions 26 and 27.After a sustaining frame has been introduced into the tube insubstantially a horizontal position, the frame is then rotated about across axis into a substantially vertical plane. This forces the exteriortube 13 to acquire the contour of the sustaining frame.

In the event the tube 13 is of unilexed contour less in diameter thanthat required by the sustaining frame, then the sustaining frame whenrotated into position widens the gap 15 and forces the tube 13 to expandinto the proper circular size. Sometimes the sustaining frame issomewhat smaller than the unflexed tube. I then provide particular meansfor drawing the external tube 13 into tight relationship with one ormore of the sustaining frames.

For that reason, one of the angles 18, for example, is pierced .toreceive an eye bolt 31 having a nut 32 thereon and connected to a linkchain 33 designed in one position to pass through a characterizedopening 34 in the other angle 19. When an appropriate link is caught inthe angle 19 and the nut 32 is tightened, the angles 18` and 19 aredrawn toward each other and the tube 13 is contracted and flexed intoappropriate abutment with the adjacent sustaining frame 21. A number ofdrawn-down devices such as the chain and eye bolt arrangement can beprovided along the length of the tube 13, so that when the tube andsustaining frames are all in close engagement, the tube itself is of theproper cross sectional shape. In either case, when all of the sustainingframes are in position, the tube partakes of a relatively rigid beamcharacteristic for its entire length.

By a reverse process, the nut 32 can be slacked otf and the chain 33disengaged, or in any case the sustaining frames can be rotated and thenlongitudinally withdrawn from thetube 13.

The tube can either first be stiifened, as indicated, by the positioningof the sustaining frames, and then lowered into the ditch, or it canfirst be installed in the ditch and the sustaining frames added later.In any event, it is desired to have a number of similar tubes 13available in a single ditch. A preceding tube 36 (FIGURE 1) isconsidered to be already in position and, like its fellow tubes,contains at one end an interior supporting band 37 in position so thatthe adjacent end 38 of a succeeding tube can encompass the band 37 andwill thus be held in correct alignment with regard to the preceding tube36. One end of the tube 13 is thus properly supported and sustained. Tosupport and sustain the other end, I provide a ternporary blockarrangement 39. This conveniently can be various blocks readilyavailable on the job site and disposed when the tube 13 is initiallyinstalled so that the center line 14 of the tube is exactly at the rightlocation. Because of variations in the bottom 8 of the ditch, it may benecessary to use a number of diiferent blocks 39 to be sure that thecenter line of the finished conduit will be well established by theinitial positioning of the successive tubes 13.

Since concrete when poured around the tube 13 may tend to shift the tubelaterally and tends to lift the tube 13 by reason of buoyant force, Iprovide particular means for additionally positioning and restrainingthe tube. Adapted to rest against the side walls of the ditch `aresubstantially identical side plates 41 and 42 utilized in mirrorsymmetry. These plates are conveniently of timber, although they can beof metal, and are of sufficient breadth horizontally and depthvertically to afford a large bearing surface against the interior Walls9 and 11 of the ditch. At their lower ends the plates 41 and 42 areprovided with wedge blocks 43 and 44 having inclined faces 46 and 47,respectively. When initially installed, the side plates 41 and 42 areurged downwardly individually and in such a fashion that they becometangent to the exterior surface of the tube 13. Both of the wedge blocks43 and 44 actually engage the tube 13 above the horizontal `center linethereof. Due to variations in the ditch walls, the plates 41 and 42 maybe relatively high or relatively low or in mutually differentelevations. They afford a transverse component as well as a verticalcornponent of positioning restraint. If desired, the tube wall adjacentthe blocks 43 and 44 can be backed up by wedges 50 jammed between thetube wall and the frame 21.

When the Wedge blocks 43 and 44 have been appropriately wedged so as tocontact the tube and so as to abut the sides of the ditch, they are soheld by frictional loading. The angle of the faces 46 and 4'7 may besufficiently low to assure stability, but preferably a strut 51Vspansthe ditch from side wall to side wall above the tube 13. The strut 51includes an outer tube 52 carrying an enlarged base 53 adapted to abutthe plate 42 and likewise carries a screw shaft 54 threadedly engagingthe tube 52 and having a pivot engagement with a foot 56 designed toabut the plate 41. A turning wheel 57 is xed on the screw shaft 54 andhas apertures for the receipt of a turning bar. A block 58 asists in theinitial positioning of the strut. When the strut 51 is so installed andthe wheel 57 is barred over, the length of the strut is increasedsufficiently so that the base 53 and the foot 56 force the plates 41 and42 rmly against the side walls of the ditch. In this fashion the wedgeblocks 43 and 44 are suitably anchored. The tube 13 is not onlysupported from below by the blocks 39, but is transversely positioned inthe ditch and is prevented from lifting by the wedge blocks.

When one or more lengths of tube 13 have been appropriately laid on theproper center line as described, concrete is poured into the ditch. Forthis purpose there is provided a travelling concrete hopper 61 having aforwardly inclined leading wall 62 and a vertical trailing wall 63.These latter walls are connected by appropriate side walls 64 and 66 toform an open-top hopper in the usual fashion.. Preferably, the wall 62is continuedby a forward vertical wall 67 having an arcuate cutout 68substantially matching the desired outer contour of the upper portion ofthe finished pipe. While the contour can be completely arcuate, it isusually preferred to provide side wings 71 and 72 (FIGURE 2). The rearwall 63 is likewise provided with a cutout edge 73 of substantially thedesired configuration for the outside of the nished pipe. Joining therear wall 63 is a curved forming screed '74 overlying the tube 13 andextending for a substantial distance to the rear ofthe wall 63.Appropriate braces 76 are provided for sustaining the position of thescreed plate 74 and the rear wall 63 of the hopper 61.

To support the hopper and screed plate at the desired relationship withthe tube 13, there are 'provided supporting rods 7'7 and 78 acting asrunners along the tube 13 and resting directly thereon. The runners areconnected by a frame 79 to the hopper 61, so that the load on the hopperis at least partially transmitted to and borne by the runners 77 'and78. In order to advance the hopper on the tube 13, a hitch 81 isprovided on the hopper frame 79 for engagement by a hook 82 connected bya cable 83 to a suitable winch or other advancing mechanism (not shown).

Since it is a preferred technique to vibrate the concrete being placed,the hopper frame 79 carries a manifold 92 receiving compressed airthrough a hose 93 from any suitable source and under the control of avalve 94. A number of vibrator headsVA are connected to the manifold 92by appropriate hoses. For example, a vibrator head 96 is disposed on theforward wall 62 of the hopper, whereas lateral vibrator heads 97 and 98are located below the hopperf61 and to either side of the tube 13,preferably below the center thereof. While a pneumatic vibrator has beendescribed, mechanical or electric vibrators can equally well be used.

After the tube 13 has been blocked in position and has been connected toa preceding tube, the hopper 61 is provided with a suitable supply ofconcrete for placement. This concrete discharges onto and around theplaced tube 13 and flows by gravity into a position occupying the bottomof the ditch 8, assisted, if desired, by operation of the vibrators 96,97 and 98. Concrete 101 is introduced into the hopper 61 from anysuitable source in batches or continuously as it is placed. The lower orinvert portion of the pipe is thus constituted and formed of concreteflowing between the pipe 13 and the adjacent bottom and side walls ofthe ditch. The concrete piles up over the pipe completely to surroundthe tube 13.

As the pouring action ensues, tension is put on the cable 83 and thehopper 61 is advanced toward the left in FIG- URE 1. As the hopperadvances, concrete is continually distributed around the subjacent tube13 and the upper surface of the resulting pipe is formed and trowelledto an appropriate finish by the forming screed 74. The concretedischarged from the forward portion of the hopper takes an angle ofslump or repose resulting from some of the material travelling ahead ofthe advancing hopper. The pipe 13 immediately below the hopper tends tobe supported from below by concrete as the hopper advances. During thistime, the wedge blocks 43 and 44 are particularly effective to precludelifting of the pipe. Just before the concrete has advanced far enough toencounter the blocks 39 and at which time substantially all of the tube13 is well supported, the blocks 39 are removed. A subsequent section102 of tube is put into position and itself is lined up by surveyingmethods and is appropriately blocked and braced. A smooth junction ismade between the pipe 13 and the pipe 102. Before further advance of thehopper, the strut 51 and the subjacent block 58 are removed. Also, theside plates 41 and 42 are similarly removed. The plates and strut aremoved forwardly for subsequent installation on an advance section oftube. The hopper thus slides smoothly forwardly on the supporting rods77 and 78 and on the placed concrete and continuously provides concretefor flow around and on top of the positioned tube.

After the concrete has had time to set, operators working within thetrailing tube, such as 36, remove the sustaining frames 21 and bysuitable jack means pull the angles 18 and 19 inwardly to deform andpartially collapse the tube 36. The sustaining frames are rotated abouta transverse axis and are moved out endwise. The collapsed tube, asshown in FIGURE 5, is of sufliciently small compass as to be removedendwise through the pipe already formed. The removed tube is thencarried forwardly for subsequent use, as are the sustaining frames. By arepetition of these operations, an indefinite length of continuous pipecan be poured in place on good and accurate alignment and with asusbtantially smooth continous inside configuration to afford goodhydraulic characteristics. Finally, the finished pipe can be coveredwith earth to leave the surface as before.

In many instances it is desirable to have the gap in the tube at thetop, but there are other cases in which, as shown in FIGURES 6, 7 and 8,the tube 113 is positioned in the trench 114 with the gap 116 at thebottom. The sustaining frame units 118 are also inverted from theirprevious positions. The remaining part of the structure is substantiallyas before, except that the gap 116 instead of being closed by a fixedplate 16 is closed by a travelling plate 121. This continues the arcuateconfiguration of the tube 113 and can be provided with a number of airreleasing apretures 122. The plate 121 is guided and positioned byangles 123 and 124 corresponding to and substantially identical with theangles 18 and 19. Additionally, guide bars 125 fastened to the plate 121ride against the tube edges at the gap 116. The forward por- 6 tion ofthe plate 121 has a connector 126 to which a draft cable 127 is attachedso that the plate 121 can be advanced relative to the pipe 113 by asliding movement on the angles 123 and 124 serving as guide rails. Avibrator 130 is fitted on the plate 121.

In the operation of this form of device, it is possible t0 dispense withthe blocks 39 and instead to use a jack 131 having a base restingdirectly on the bottom of the ditch 6. The jack extends through the gap116 and is adjustable against the top inside of the tube 113. In thisway, the tube can easily be brought to exact alignment. As before, thejack is removed when the tube is Well supported by concrete.

Before the concrete is poured and before the travelling plate 121 isadvanced, the bottom of the ditch is finally inspected through the gap116 and any debris, such as clods, is removed. This is an advantage ofthe bottom gap arrangement. The travelling plate is temporarilysustained on hook bolts 136 depending from cross bars 137. These areremoved as soon as sufficient concrete is beneath the travelling plateto provide an upward thrust.

The concrete is placed as before and comes to an initial set. Thereafterthe tube is removed after the sustaining frames 118 have been taken out.For this purpose, the angles 123 and 124 are drawn together, or partlyt0- gether, by cross chains 138. A dolly 141 is then put into positionunder each chain 138 near the tube ends. The dolly is in effect a bellcrank on pneumatic wheels. Each dolly is brought into place at an angleand finally one of its lever arms engages one of the chains 138. Theother dolly lever arm is then lowered so that all wheels are on thejust-cast pipe. This tensions the chain 138 further and lifts one end ofthe contracted tube slightly so that its weight is borne by the dolly.With a dolly at y each end, the contracted tube can easily be wheeled onthe pipe to a point of removal for reuse.

What is claimed is:

1. A pipe forming machine for use in a ditch having side wallscomprising a straight collapsible tube having a longitudinal gaptherein, means for supporting said tube above the bottom of said ditch,means for engaging the sides of said ditch and said tube above thecenter thereof, a sustaining frame inside said tube, means for holdingsaid tube against said sustaining frame to make said tube alongitudinally rigid supporting beam, a concrete hopper, means forsupporting said hopper solely on said tube for advancementlongitudinally thereon in a predetermined direction established by saidtube and independent of the bottom and side walls of said ditch, aforming screed trailing from said hopper and overlying said tube atsubstantially a fixed radial distance therefrom, and means supported onsaid tube and spanning said gap therein.

2. vA pipe forming machine for use in a ditch having side Iwallscomprising a straight tube having a longitudinal gap therein and adaptedto be circumferentially flexed i-nto different cross sectional shapes, asustaining frame of fixed cross sectional shape inside said tube, meansfor holding said tube against said sustaining frame to make said tube alongitudinally rigid supporting beam, means supported on said tube andspanning said gap therein, a concrete hopper, means for supporting saidhopper entirely on said tube for -advancement along said tube in a pathestablished solely by said tube, a forming screen trailing from saidhopper and overlying said tube at substantially a fixed radial distancetherefrom, means for supporting said tube at a fixed distance above thebottom of said ditch, and means engaging said side -walls for holdingsaid tube Ifrom rising Iin said ditch.

3. A pipe forming machine for use in a ditch having side wallscomprising a tube of flexible material and having a longitudinal gaptherein, means forming supports within said tube alongside said gap, a`plate engaging sai-d supports and spanning said gap, a sustaining frameof fixed cross sectional shape inside said tube, means for holding saidtube lagainst said sustaining frame and mak- 7 ing said tube alongitudinally rigid supporting beam `of regular contour, means engagingsaid side .walls for holdin said tube from rising in said ditch, aconcrete hopper, means -for supporting said concrete hopper entirely onsaid tube foradvancement therealong, and a forming screed trailing rfromsaid hopper and overlying said tube.

4. A pipe forming machine for use in a ditch having side wallsand abottom comprising a deformable tube having a longitudinal gap therein, aplate supported on and closing said gap in said tube, means erectablewithin and removable from said tube for hold-ing said tube in a tixedcr-oss sectional shape and to make said tube a longitudinally rigidsupporting beam of regular contour, means engaging said side Walls andsaid bottom for positioning said tube within said ditch, a concretehopper, means for supporting said concrete hopper entirely on said tubefor advancement thereon, and a forming screed trailing from said hopperand overlying said tube. Y

5. A .pipe lforming machine for use in a ditch having side Walls and abottom comprising a tube having a longitudinal gap therein, a plateengaging said tube adjacent to and closing said gap, means adapted topass longitudinally through said tube and erecta-ble into positionstransversely of said tubefor holding said tube in a fixed crosssecti-onal shape and to make said tube a rigid support of regularrectilinear contour, means engaging said side walls andsaid bottom rforpositioning said tube within said ditch, -a forming screed adapted toroverlie said tube, and means engaging said tube for entirely`supporting said 4forming screed Afor advancementalong said tube in apredetermined spaced relationship therewith.

6. A pipe forming machine for use in -a ditch having side walls and abotoom comprising a tube of exible material land having a longitudinalgap therein extending from one end to the other, means on said tubeforming guideways along said gap, a plate engaging said guidelways andclosing said gap, a sustaining frame adapted in lone position to passlongitudinally through said tube and in another position t-o hold saidtube in iixed cross sectional shape and to make said tube a rigidsupport of regular contour, lbl-ocks removably interposed between saidbottom and said tube for supporting said tube in a predeterminedposition in said ditch, means including a strut engaging said side wallsfor holding saidtube in predetermined position in said ditch, a formingscreen extending between said side walls and overlying said tube, andmeans engaging said tube for entirely supporting said forming screed -onsaid tube at a predetermined distance therefrom.

7. A .pipe forming machine for use in a ditch having side walls andabottom comprising a tube having a longi-y tudinal gap therein along thebottom of the tube, means :for supporting sa-id tube in said ditchincluding a jack resting on the bottom of said ditch and extendingthrough said gap into abutment with the inside of the tube at the topthereof, a concrete hopper and screed mechanism, means for supportingsaid concrete hopper and screed mechanism on said tube for advancementthereon, a travelling plate engageable with said tube and extendingacross said longitudinal gap, means tor advancing saidI 8. A pipeforming machine as in claim 7 in lwhichy said tnavelling plate isperforated.

9. A pipe forming machine as in claim 7y in which said tube isheld downin said ditch by means engaging said tube above the center thereof andon opposite sides of the center thereof.

10. A pipe forming machine -for use in a ditch having side walls and labottom comprising an elongated tube, means for holding said tube as alongitudinally rigid supporting beam of predetermined contour, lmeansengaging said bottom and said tube yfor holding said tube in apredetermined position in said ditchvindependently of the position ofsaid bottom and said walls, a concrete hopper and 'screed mechanism,means solely engaging said tube for entirely supporting said concretehopper and screed vmechanism on said tube, and means for advancing saidhopper and screed mechanism along said ditch in a path -xed by said tubeand independent of said bottom and said side walls.l Y

11. A pipe forming machine for use in a ditch having side walls and a.bottom comprising an elongated tube solely engaging said tube andindependent of said bottom and said side walls for entirely supportingsaid concrete hopper and screed mechanism on said tube, and means foradvancing said concrete hopper and screed mechanism along said tube in apath vestablished solely by said tube.

References Cited by the Examiner v UNITED STATES PATENTS 545,978 9/95Ransome 25-32 942,922 12/09 OConnor 25-131.5 1,191,731 7/'16 Ransome25--12 1,520,840 12/24 Mfurray 25-128 1,570,915 1/26 yNose 25-12'81,734,773 11/29 Murray 25-128 2,114,785 t 4/38 Porter 25131.6 2,574,21311/51 Jerner 25-32 2,843,913 7/58 IBarr-on 25-131.5 `2,968,081 1/61Williamson et al. '25-321 2,987,793 =6/ 61 Martin et al. 25-32 3,032,8525/62 Hanson 25-32 3,049,783 8/62 Hanson 25-32 v3,089,213 5/'63Williamson 25-32 I. SPENCER OVERHOLSER, Primary Examiner.

ROBERT F. WHITE, MARCUS U. LYONS, Examiners.

10. A PIPE FORMING MACHINE FOR USE IN A DITCH HAVING SIDE WALLS AND ABOTTOM COMPRISING AN ELONGATED TUBE, MEANS FOR HOLDING SAID TUBE AS ALONGITUDINALLY RIGID SUPPORTING BEAM OF PREDETERMINED CONTOUR, MEANSENGAGING SAID BOTTOM AND SAID TUBE FOR HOLDING SAID TUBE IN APREDETERMINED POSITION IN SAID DITCH INDEPENDENTLY OF THE POSITION OFSAID BOTTOM AND SAID WALLS, A CONCRETE